Prior art wireless systems only permit authorized wireless terminals to have access to the wireless network. In order to permit a wireless terminal access to the network the wireless terminal must be authenticated. The term “authentication” is used herein in the conventional manner, e.g., the process of verifying that an entity is really that who it alleges it is. Authentication may be needed multiple times during the duration of a call, e.g., originally when the call is initiated and thereafter each time the wireless terminal makes a transition across any defined boundary in the network.
Authentication is achieved by comparing information derived from secret information stored in the wireless terminal with the same derived information existing somewhere else in the network. Typically the derived information must be transmitted each time a new authentication is required for a particular wireless terminal during the course of a single call from the storage location of the derived information that is “closest” to the location of the comparison, where “closest” is in terms of network hierarchy.
A wireless terminal communicates with a base station via an airlink. If the base station is not the location of the comparison, the base station must forward information from the wireless terminal to the location of the comparison for use in the comparison. The location in the network in which the derived information is stored is typically in a so-called “visitor location register” (VLR). The derived information is generated in the network at a so-called “home location register” (HLR) or other authentication center as may be present, depending on the particular network design. When a wireless terminal crosses a network boundary that separates the area served by a first VLR to the area served by a second VLR, the first VLR may forward the derived information to the second VLR for its use. Alternatively the second VLR may obtain its own derived information from the HLR. Note that the HLR may act as a VLR when the wireless terminal first powers up in an area directly served by the HLR.
Disadvantageously, the cost of the prior art network is high, because of the various specialized entities therein and the complex control procedures required.